Washington: A devastating puncture that allowed hot air inside the left wing may be the reason behind disintegration of space shuttle Columbia on February 1 that killed Kalpana Chawla and six other astronauts.

Investigators, in a first significant determination on the cause of the crash said Columbia broke up during re-entry, possibly because of the presence of super-heated air or plasma inside the left wing.

The new theory for the crash of the space shuttle effectively rules out the loss of heat resistant tiles as was initially put forth as a possible cause for the disaster.

"Heat transfer through the structure as from a missing tile would not be sufficient to cause the temperature indications seen in the last minutes of flight," NASA (National Aeronautics and Space Administration) spokesman James Hartsfield said.

The Columbia Accident Investigation Board was now studying various scenarios that could cause a breach allowing plasma, that surrounds a spacecraft during re-entry, into the wheel compartment or elsewhere in the wing, he said.

Moments before Columbia disintegrated, mission control in Houston detected an unusually high heat build-up in the shuttle's left wing, which could have indicated missing or damaged tiles.

Officials have previously focused on an unusually large chunk of foam that broke off Columbia's external fuel tank on lift-off.

Video footage showed it struck part of the shuttle's left wing, including its toughened leading edge and the thermal tiles covering the landing gear.

PTI